About Crayfish
The American Signal Crayfish, and other species of non-native Crayfish, have been introduced to England's waters since the mid 1970's to be farmed as a source of meat. This proved to be one of the biggest ecological disasters ever caused by humans, with the non-native Crayfish escaping the ponds and lakes that they had been introduced into and instead invading many of the waterways in the south of the country. The Signal Crayfish have now taken over a huge percentage of the rivers, canals, lakes and ponds not only in the south of England but also in the rest of the country. They have been sighted as far north as Scotland, a real sign of their invasiveness and ability to adapt to their environment.
Not only are Signal Crayfish larger, more aggressive, and more dominant then the native English White Clawed Crayfish, but they also carry a fungal disease called Aphanomyces astaci. The American Signal Crayfish are actually immune to the effects of this disease, they just carry it upon their bodies, whereas the White Clawed Crayfish is not so lucky, and will eventually die when it comes into contact with this disease, which is also known as the crayfish plague.
| The Non-Native Signal Crayfish | The Native White Clawed Crayfish |
Signal Crayfish are currently thriving in English waters, whilst the native White Clawed Crayfish has nearly been completely wiped out. Not only does this non-native creature do damage to the native animal but it also wreaks havoc in the general river and water environment. The Signal Crayfish will burrow deep into river banks causing great damage and erosion to the landscape. They also eat many fish and other creatures in the waters, creating an unnatural balance in the water ecosystem. Signal Crayfish can also feed on algae and plantlife in the water, which the native crayfish may not do, meaning that the non-native creature has a far greater chance of living and thriving in our waters due to the greater amount of food that is available for it.
Overall, this means that the White Clawed Crayfish which is native to our waters needs all the help it can get in enabling itself to re-establish a foothold in our eco-system, especially considering that the non-native creature was introduced by us, as what should have been a form of farmed food. Trapping the Signal Crayfish is one of the few effective and eco-friendly ways to remove this pest from our waters, and this practise should be engaged in whenever possible.